Automatic sampler apparatus

ABSTRACT

A system for injecting sample fluids into an analyzer and processing the analysis data is disclosed. The system comprises a fluid sample analyzer, a sample storage module for a number of fluid samples, an injection module by which samples are injected into the analyzer, a data recording or processing device, and a control module for governing and sequencing the operation of the system. The storage module houses a plurality of sample containing trays which can be loaded with samples remote from the system. A gas operated purging system is employed for minimizing the quantity of residual material injected into the analyzer with successive samples.

United States Patent Pecsar et al.

[451 Apr. 15, 1975 AUTOMATIC SAMPLER APPARATUS Inventors: Raymond ErnestPecsar, Walnut Creek; Brent Earl Wadsworth, Concord, both of Calif.

Assignee: Varian Associates, Palo Alto, Calif.

Filed: Mar. 5, 1973 Appl. No.: 337,799

U.S. Cl. 73/425.6; 23/230; 23/259; 134/22 C; 134/34 Int. Cl. r. B08b9/02; GOln l/OO Field of Search 7-3/422 GC, 423 A, 425.6; 23/253 R, 259R; 134/22 R, 22 C, 34, 37

References Cited UNITED STATES PATENTS 11/1969 Mutter et al. 73/423 A8/1973 Harris, Sr. et al. 73/423 A Primary ExaminerS. Clement SwisherAttorney, Agent, or FirmGerald M. Fisher; Stanley Z. Cole [57] ABSTRACTA system for injecting sample fluids into an analyzer and processing theanalysis data is disclosed. The system comprises a fluid sampleanalyzer, a sample storage module for a number of fluid samples, aninjection module by which samples are injected into the analyzer, a datarecording or processing device, and a control module for governing andsequencing the operation of the system.

The storage module houses a plurality of sample containing trays whichcan be loaded with samples remote from the system. A gas operatedpurging system is employed for minimizing the quantity of residualmaterial injected into the analyzer with successive samples.

2 Claims, 9 Drawing Figures PATENTEUAPR 1 51975 sum 3 or 5 suznunrg;

N3 Sq EOE PATENTEDAPR I 51915 3.877, 3 1 0 sum 5 1 5 FIG.9

AUTOMATIC SAMPLER APPARATUS BACKGROUND OF THE INVENTION 1. Field of theInvention The present invention relates to the analysis of sample fluidsand more particularly relates to systems for controlling theintroduction of sample fluids into an analyzer.

2. Prior Art Systems for supplying fluid samples for analysis byequipment, such as chromatographic analyzers, have been proposed by theprior art. Some prior art systems have employed a syringe forintroducing a predetermined quantity of sample fluid into the analyzerequipment. Sample fluids to be analyzed were disposed in separate closedsample containers and successive individual fluid samples were removedfrom their containers, supplied to the syringe, and injected into theequipment.

It is imperative in most sample analyses that the sample fluid beinganalyzed be as free as possible from any type of foreign substance.Accordingly, the injection syringe was required to be thoroughly purgedof one sample fluid and/or any residual cleansing solvent before asucceeding sample was placed in the syringe. The syringes employed forsample fluid injection were quite delicate because of the extremelysmall quantities of sample fluid they handled, e.g. quantities of from 550 microliters, this made manual operation and purging of the syringesboth tedious and time consuming. Furthermore, when large numbers ofsamples were being successively analyzed, a skilled operator wasrequired to attend the equipment and perform the tedious and repetitivetask for purging and filling the syringe.

In order to increase the speed and efficiency of the analysis ofmultiple fluid samples, mechanized syringe handling systems wereproposed. The purpose of such systems was to reduce the amount ofoperator time required in connection with the analysis procedures and toreduce equipment failures, e.g. the syringe breakage and damage whichinevitably resulted from frequent handling. 5

The mechanized systems generally consisted of a supporting tray forsample containers and an injection syringe manipulating mechanism whichfunctioned to enable removal of sample fluid from individual containers,injection of the fluid into the analyzer and purging of the syringe. Thesample container trays were usually actuatable to index successivesample containers to a location from which fluid was transferred to thesyringe.

While the prior art mechanized systems were effective in reducing theamount of operator time required to analyze fluid samples, severalproblems relating to syringe manipulation and purging remained unsolvedand errors in sample identification due to handling by the operatorswere encountered.

In some proposals the mechanized syringe purging left undesirably largequantities of foreign materials in the samples which were injected intothe analyzers. In one type of system, for example, the syringe plungerwas mechanically reciprocated during purging to draw in the expelsuccessive charges of solvent and/or sample fluid prior to injection ofthat sample fluid into the analyzer.

In another type of system, a side arm syringe was employed and purgingwas accomplished by retracting the syringe plunger beyond the syringeside arm port after which solvent and/or sample fluid was pumped throughthe syringe barrel for a predetermined period of time.

Both of these purging procedures, while preferable to manual purging,left undesirably large quantities of foreign material in the samplefluid injected into the analyzers. ln particular it was discovered thatvolatile fluids created pump cavitation which resulted in the formationof gas bubbles in the purge fluid. This reduced the purgingeffectiveness.

In still other proposals, sample liquids were subjected to apredetermined differential gas pressure for a predetermined period oftime so that the sample liquid was forced through the injection syringeand associated conduits to effect purging. Because sample fluidviscosity varied widely, these systems were subject to expending to muchsample fluid during the purging process when low viscosity fluids wereemployed, and did not expend adequate quantities of fluid for completepurging of highly viscous samples. In circumstances where highlyvolatile fluid samples were analyzed the partial pressure of the fluidvapor tended to substantially increase the applied pressure differentialand the purge volume was thus difficult to accurately control.

SUMMARY OF THE INVENTION The present invention provides a new andimproved sample analysis method and system wherein fluid samples to beanalyzed need not be loaded by the operator of the analysis system andconfusion as to the identify of fluid sample analysis results isminimized; sample fluid injection equipment and associated sample flowconduits are purged by a controlled volume of purging fluid so thatsamples of fluid injected in the apparatus are nearly uniformly pureregardless of differences in sample fluid viscosity and/or volatility;the volume of sample fluid injected into the analyzer is accuratelygoverned by adjustable dosage controls; damage to syringe-like elementsof the system resulting from misalignment of sample containers or otherfluid receivers and the styringe-like elements is avoided; and numerousdifferent sample fluids can be analyzed automatically without requiringfull time attendance of a skilled operator.

In a preferred and illustrated embodiment of the invention a system isprovided which comprises a sample analyzer, a sample injection module bywhich a sample of fluid to be analyzed is injected into the analyzer, asample storage module which houses a number of discrete samples of fluidto be analyzed and which supplies sample fluid to the injection module,a sample analysis computer which may be programmed to partially governoperation of the system, and an electronic control module which governsoperation of the components of the system.

The sample storage module receives a plurality of separate samplestorage trays, or racks, in which a number of sample containers may beplaced. The trays or racks are detachably connected to the storagemodule and as such can be loaded with samples remote from the analysissystem. The trays or racks can be loaded with containers in laboratoriesand forwarded to the analysis system. The operator of the system thusdoes not have to load or unload trays and is not required to account forthe identify and location of any given fluid sample.

The sample storage module is detachably connected to the injectionmodule and sample fluid which is withdrawn from an individual containerin the storage module is conducted into the injection module via asample conduit. The injection module includes a syringe connected to theconduit which injects a predetermined dose of the fluid into theanalyzer. Prior to the injection of a sample, the sample conduit and theinjection syringe in the module are purged to remove residual fluid froma previous cycle of the system.

In the preferred and illustrated embodiment of the invention, purgingfluid (either sample fluid or a solvent) is located in a container whichis closed by a septum. A syringe-like dipper tube assembly is advancedinto the container through the septum. The dipper tube assembliescomprises a first tube which communicates with the injection syringethrough the sample conduit and a second tube which is connected with apurging system.

When the dipper tube assembly is advanced into the container, thepurging system is then operated to expose the fluid in the container toa predetermined volume of gas at a predetermined pressure, preferably bydischarging an accumulator into the container via the second dipper tubeconduit. This creates a pressure differential across the sampleextracting dipper tube, the conduit and the injection syringe so that apredetermined quantity of the fluid is directed through the-injectionmodule. The pressure differential across the purging fluid diminishes asfluid flows from the container and when the pressure differential hasdecayed to about zero, a predetermined quantity of the fluid has beerflowed through a conduit and injection syringe. It has been found thtthe use of a purging volume approximately times the volume of the sampleconduit and injection syringe consistently reduces the quantities ofresidual material in the system extremely low extremelylow levels.

Another important feature of the invention resides in the positioning ofthe injection syringe plunger during the purging process. In thepreferred and illustrated embodiment of the invention the injectionsyringe is a side arm syringe and the projecting end of the syringeplunger is at least partially aligned with the side arm port in thesyringe barrel so that purging fluid directed through the syringeimpinges directly on the end of the plunger. This has the effect ofscouring the plunger end to dislodge any remaining material fromprevious injection or purging cycle and to remove that material from thesyringe.

While the system is being purged, the injection syringe directs thepurging fluid into a drain system which retains the fluid and minimizesthe amount of fluid vapor in the atmosphere around the injection module.When purging has been completed the injection syringe is operated tomove the plunger of the syringe to a position at which a controlled doseof the sample liquid is disposed in the syringe after which the syringeis removed from the drain and inserted into the analyzer inlet. Thepredetermined dose of the sample is then injected into the inlet foranalysis.

Another feature of the inention is the provision of a sample analysissystem wherein a control module governs operation of sample storage andinjection modules and is capable of interrelating these operations witha computer. The system is constructed and arranged so that the entireanalysis of multiple samples can be controlled by a programmed computerwhile at the same time permitting system operation by an operator.

Other features and advantages of the invention will be apparent from thefollowing detailed description of a preferred embodiment made withreference to the accompanying drawings which form a part of thespecification.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of aninjection module;

FIG. 2 is a cross sectional view seen approximately from the planeindicated by the line 22 of FIG. 1;

FIG. 3 is a cross sectional view seen approximately from the planeindicated by the line 33 of FIG. 1;

FIG. 4 is a cross sectional view seen approximately from the planeindicated by the line 4-4 of FIG. 3;

FIG. 5 is a cross sectional view seen approximately from the planeindicated by the line 5-5 of FIG. 3;

FIG. 6 is a plan view of a sample storage container module;

FIG. 7 is a cross sectional view seen approximately from the line 77 inFIG. 6;

FIG. 8 is a cross sectional view of part of a dipper tube assembly; and

FIG. '9 is a schematic diagram of a fluid pressure system containedwithin the injection and storage modules.

DESCRIPTION OF A PREFERRED EMBODIMENT An automatic sample systemembodying the present invention is illustrated in FIG. 8 as comprising asample analyzer 12a, which may be, for example, an apparatus foranalyzing a fluid sample by liquid or gas chromotography; a sampleinjection module 14 by which a sample of fluid to be analyzed isinjected into the analyzer 12a; a sample storage module 16 which housesa number of discrete samples of fluid to be analyzed and which suppliessample fluid to the injection module.

In brief, the system 10 operates in the following manner: The injectionmodule and sample storage module are connected to each other in adesired orientation and are detachably connected to the analyzer 12a,which may be of any suitable or conventional type or construction, and anumber of containers of sample fluid are disposed in the storage module.Automatic operation of the system is then initiated by the operatorwhich results in a predetermined quantity of sample fluid from onecontainer inthe storage module 16 being extracted and delivered to theinjection module 14 from which a predetermined quantity of the sample isinjected into the analyzer l2a.The analyzer 12a processes the samplefluid and data resulting from the analyzer process is fed to a computerand/or a recorder.

Prior to the injection of each fluid sample into the analyzer, the flowpassageways through which the sample passes from the storage module intothe analyzer are purged to remove substantially all traces of thepreceding sample fluid from the passages prior to the introduction ofthe next succeeding sample to the analyzer. Purging/ls conducted usingthe next succeeding sample fluid itself or using a suitable solvent andthen the next succeeding sample fluid so that the possibility ofcontaminating any given fluid sample by the preceding sample or thesolvent is minimized. The purging solvent is contained by the storagemodule like the samples and is introduced into the passages to bepurged.

The sequence of operation of the system is governed by a control module.

It should be appreciated that the brief description of the operation ofthe system has been simplified and generalized in order to provide anoverall understanding of the functions and interrelationships of thevarious modules and components of the system. The various modules andcomponents of the system are described separately below.

The Injection Module 14 The injection module 14 comprises a supportframe 30 which supports a syringe carriage assembly 32, a carriageactuator 34 and a waste receiving system 36. The syringe carriageassembly 32 includes a sample injecting syringe, described in detailpresently, which is movable by operation of the carriage actuator 34 toinject a predetermined quantity of sample fluid into the analyzer 12a aswell as to inject purging fluid into the waste receiving system 36. Theinjection module 14 is illustrated in FIGS. 1-5 of the drawings.

Referring particularly to FIGS. 1 and 3, the frame 30 is illustrated asincluding side panels 40, 42, opposite end walls 44, 46 extendingbetween the side panels, and a base section 48 extending from the endwall 46 between the side panels 40, 42. A pair of cylindrical guiderods, or ways, 50 extend between the end walls 44, 46 parallel to theside panels. The end wall 44 mounts along the face of the analyzer 12aby interconnection of the end wall 44 to the analyzer by suitableconnectors (not shown). The end wall 44 defines an opening 52 which isaligned with an analyzer sample inlet which is shown in part in FIG. 3at 12a. The sample inlet 12a is provided with an inlet port throughwhich the needle or canulla, of the injection syringe extends when asample is being injected into the analyzer. The inlet sample port iscovered by a septum as is conventional, so that in order to inject asample of fluid into the analyzer the syringe needle must pierce theseptum covering the analyzer inlet port.

The side panels 40, 42 extend away from the analyzer 12 and each definesan access port 56 and connector openings 58. Fluid and/or electricconduits extend through one or the other of the ports 56 from thestorage module 16 depending upon which of the side panels 40 or 42 isengaged with the storage module. The connector openings 58 function toenable detachable connection of the storage module to the injectionmodule by screws or other suitable fasteners which extend between themodules.

Slot 60 enables repositioning of the storage module from one side panelof the frame 30 to the other side panel without requiring disconnectionof the conduits extending between the modules during the repositioning.That is to say, the conduits can be guided from one access openingthrough the associated slot 60, and to the other access opening throughits associated slot 60 without disconnecting the conduits from theinjection module. Repositioning of the storage module with respect tothe injection module might be occasioned where the storage and injectionmodules are utilized in connection with various analyzers havingdifferent physical configurations.

Removable cover panels 62, 64 are connected to the frame 30 to shieldthe internal components of the injection module 14 when in use, and areremoved to enable access to these components for servicing andmaintenance. One or both cover panels are also removed when theinjection module is repositioned with respect to the storage module toenable manipulation of the interconnecting conduits from one accessopening to the other as described above.

The syringe carriage assembly 32 is supported on the ways 50 and isreciprocally movable towards and away from the end wall 44 to accomplishthe functions of injecting a sample fluid into the analyzer as well asto direct purging fluid into the waste system. The assembly 32 comprisesa carriage support body which is slidably mounted upon the ways 50, asyringe assembly 72 carried by the body 70, and a syringe actuatingassembly 74 also carried by the body 70.

The body 70 comprises a base 76 which extends parallel to the frame basesection 48 between the side panel 40, 42. The base 76 carries projectingtransverse flange-like portions 78, 80 through which the ways 50slidably extend. The projecting flange-like portions are spaced apartalong the body 76 to assure rectilinear motion of the carriage assembly.

The actuator 34 is preferably a single acting pneumatic ram typeactuator comprising a cylinder 84 which is connected to the frame base48 by a suitable pillow block connection and which has a piston rod 86connected to the carriage flange 78. When the actuator 34 is suppliedwith operating fluid pressure the piston rod 86 moves the carriageassembly towards the left, as seen in FIGS. 3, to advance the syringeassembly 72 toward the frame wall 44. The actuator 34 is provided withan internal return spring which functions, when the cylinder 84 isvented, to move the carriage assembly towards the right as seen in FIG.3 to the position which is illustrated in FIG. 5. At this position thesyringe assembly 72 is retracted away from the end wall 44 to the limitof its travel.

The syringe assembly 72 comprises a tubular syringe barrel 90 withinwhich a solid plunger 92 is slidably disposed. The barrel 90 and plunger92 cooperate to define a variable volume chamber 93 within the syringebarrel. The end of the syringe barrel remote from the plunger supports ahollow needle, or canulla, 94 which communicates with the chamber 93 andprojects from the syringe barrel towards the frame end wall 44. Thesyringe barrel 90 is preferably of the type known as a side arm syringeand defines a side wall port 96 through which fluid can be directed intothe chamber 93 between the plunger and the needle 94.

The syringe barrel 90 is mounted on the support body 70 by a barrelsupport member 100 and a barrel sup porting bracket 102. The syringebarrel itself is formed from glass and is graduated appropriately. Thebarrel is removably connected to the barrel support member 100 and thesupport bracket 102 for easy replacement.

A syringe needle guiding and supporting member 104 is associated withthe barrel support member 100 and functions to both guide and supportthe needle 94 as it is thrust through a septum. The member 104 is agenerally U-shaped member having legs 106, 108, which extend parallel tothe needle 94 along the support member 100, and a bight portion 11.0which extends transverse to the needle. A guiding bore 1 12 is formed inthe bight portion through which the needle 94 extends. The bore 112 isof a diameter which is just slightly larger than that of the needle sothat the needle is guided through the bore and supported by the bightportion 110. The tip of the needle 94 extends just beyond the bightportion 110 when the carriage assembly is in the position illustrated inFIGS. 1 and 3. The leg 106 extends through an opening in the supportmember 100 and carries a flange-like collar 106a which is engaged by acompression spring 114 which reacts between the collar 106a and a springabutment element 115 fixed to the body 70. The leg 106 slidably extendsthrough an opening in the spring abutment element 115 and is alignedwith an opening formed in the bracket 102 so that the member 104 mayreciprocate relative to the needle 94 against the force of the spring114.

The member 104 provides point of entry support for the needle 94 as theneedle is advanced through a septum. For example, referring to theanalyzer inlet 12a, as the carriage assembly is advanced towards theanalyzer inlet 12a the bight portion 110 of the member 104 engages theanalyzer inlet at about the same time that the tip of the needle 94engages the inlet septum. As the carriage continues to advance, theneedle is thrust through the septum while the member 104 engages theanalyzer inlet and is prevented from moving further towards the analyzerwith the needle. The member 104 thus is moved relative to the barrelsupport member 100 against the bias of the spring 1 14 and the bightportion 110 of the member remains adjacent that portion of the needlewhich is currently passing through the septum. Hence, the bight portionof the U-shaped member continually supports the needle adjacent thepoint of entry of the needle into the septum thus tends to minimize thepossibility of bending the needle as it is being advanced through aseptum.

The chamber 93 and the plunger 92 are preferably cylindrical and haverelatively small diameters since desirable sample quantities of fluidbeing injected into the analyzer are normally quite small, e.g. from to50 microliters. Accordingly, the plunger has an extremely small diameteras compared to its overall length. The plunger is supported forreciprocal movement relative to the barrel by guides which prevent theplunger from buckling under compressive loads. As seen in FIGS. 1 and 3,the plunger projects out of the syringe barrel away from the analyzer 12and through a guide tube 92' formed in a projecting leg 122 of thebracket 102. The guide tube 92' closely surrounds the plunger 92 tomaintain the plunger accurately aligned with the syringe barrel. Theplunger projects beyond the leg 122 and terminates in a radiallyprojecting flange-like end portion 92a.

The syringe actuating assembly 74 functions to reciproate the plunger 92in the syringe barrel 90 so that a predetermined quantity, or dose, orsample fluid can be injected into the analyzer 12 and to enable purgingof the chamber 93 and the needle 94. The syringe actuating assembly 74includes a plunger drive mechanism 130, an actuator 132 for the plungerdrive mechanism, and adjustable dosage stops 134, 136 which individuallyfunction to control the position of the plunger within the syringebarrel prior to the injection of a sample of fluid into the analyzer,and hence determine rather precisely the dosage of the fluid which isinjected.

The plunger drive mechanism 130 comprises a cross bar 140 which isslidably disposed on the ways 50 and plunger engaging elements carriedby the cross bar which cooperate to cushion compressive shock loadingswhich might otherwise be applied to the plunger, as well as to withdrawthe plunger from the syringe barrel. The plunger engaging elementsinclude a plunger guide member 142, a plunger engaging leaf spring 144and a spring backup member 146 all of which project from the cross bartowards the plunger end portion 92a. The plunger guide 142 defines abore through which the plunger 92 extends and the flange 92a at theprojecting end of the plunger is interposed between the guide member 142and the leaf spring 144.

The actuator 132 is operative to shift the cross bar and its relatedelements along the ways 50 relative to the carriage to reciprocate theplunger 92 with respect to the plunger barrel. When the plunger 92 iswithdrawn from the syringe barrel and moved towards the right, as viewedin FIG. 3, to the position illustrated, the guide 142 engages theplunger flange 92a to transmit plunger retracting force from theactuator 132 to the plunger.

As the actuator 132 is operated to shift the cross bar and associatedelements towards the left as seen in FIG. 3, the plunger 92 is thrustinto the syringe barrel and the force from the actuator is transmittedto the plunger 92 through the leaf spring 144. When the actuator isinitially operated to advance the plunger 92 into the syringe it has aspring constant so that the leaf spring 144 deflects only very slightly.The backup member 146 is positioned beyond the leaf spring so that unduedeflection of the spring will not occur.

The actuator 132 is preferably a double acting pneumatically operatedram which provides for positive positioning of the syringe plunger 92 inthe barrel. The actuator comprises a cylinder 150 ported at both endsand fixed to the carriage body 70, and an internal piston supporting apiston rod 152 connected to the cross bar 140. The piston rod 152reciprocates the cross bar 140 relative to the carriage body.

The piston rod can be prevented from moving relative to the cylinder byfluid pressure forces applied to both sides of the piston when desired.This positively maintains the cross bar 140 at a predetermined locationand prevents the plunger from moving relative to the syringe barrel.

The carriage body 70 is provided with a slot 156 (see FIG. 1) whichenables the guide 142, leaf spring 144 and backup member 146 to beshifted along the direction of movement of the plunger 92 withoutinterferring with the carriage body.

The dosage stops 134, 136 are identical and accordingly only the stop136 is described in detail. The stop 136 is preferably formed by asolenoid 160 which is slidably disposed in an elongated slot 162 formedin the carriage body 70 (see FIG. 1). A clamp mechanism 164 isassociated with the solenoid 160 to enable the solenoid to be clampedand maintained at any desired position along the slot 162.

The solenoid 160 includes an armature 168 in the form of a pin, or stopelement, which, when the solenoid is actuated, projects from thesolenoid 136 into the path of movement of the cross bar 140 to preventthe plunger 92 from being advanced further into the syringe barrel. Thepin 168, in its extended position, is illustrated in FIG. 3. When thesolenoid 160 is deenergized, the pin 168 is retracted by operation of areturn spring (not illustrated) and the cross bar 140 is movable tofurther advance the plunger 92 into the syringe barrel.

When the plunger drive mechanism is in its position illustrated in FIG.3, the cross bar is at the limit of its travel towards the frame end 46and the plunger 92 is retracted from the syringe barrel to its limit oftravel. As illustrated in FIG. 5, at the limit of plunger travel in theretracted direction, the projecting tip of the plunger 92 is adjacentthe side arm port 96 of the syringe barrel so that fluid can be directedthrough the side arm 96 into the chamber 93 and though the needle 94.This is the manner by which the syringe barrel is purged. It should benoted that the tip of the plunger 92 is impinged on by the fluid passingthrough the side arm port 96 and the turbulent fluid flow at the tip ofthe plunger produces a scouring action on the plunger tip which aids inremoving any residual materials which may otherwise cling to the plungertip.

After purging is accomplished, one or the other of the dosage stops 134,136 is energized and the actuator 132 is operated to advance the plunger132 into the syringe barrel until the cross bar 140 abuts the projectingpin 168 of the energized dosage stop. This prevents further movement ofthe plunger 92 into the syringe and provides a predetermined quantity ofsample fluid in the chamber 93 and needle 94 which can be then objectedinto the analyzer 12. The piston of the actuator 132 is then locked inposition by the application of substantially equal fluid pressure onboth sides of the piston and the dosage stop solenoid is deenergized toretract the pin 168. The application of fluid pressure to both sides ofthe actuator piston relieves any shearing force exerted by the cross baron the pin 168 so that the pin is freely retracted.

The carriage body 70 is then advanced to thrust the needle 94 into theanalyzer inlet after which the actuator 132 is again energized toadvance the plunger 92 into the syringe barrel from the dosage stoplocation of the plunger to the limit of the plunger travel towards theanalyzer. A predetermined dose of fluid is thus injected into theanalyzer. The limit of plunger travel, in the preferred and illustratedembodiment, occurs when the cross bar 140 encounters the mounting nutfor the actuator 142; however, any other suitable abutment can beprovided if desired. The individual operation of the dosage stops allowstwo different sample dosages to be preset without requiring readjustmentof the dosage stop positions.

As described previously with reference to FIGS. 1, 3 and 5 the syringebarrel and needle are purged by flowing fluid through the side arm 96,the chamber 93 and the needle 94 prior to the injection of apredetermined dose of the sample fluid into the analyzer 12. The purgingoperation is necessary to assure that the sample fluid injected into theanalyzer is as pure as practical. During the purging operation, thepurging fluid, whether it be a solvent or sample fluid, is expelled fromthe needle 94 into the waste system 36.

The waste system 36 is particularly adapted to receive purging fluidwhich is relatively volatile at room temperature and atmosphericpressure and to prevent the vapor of such fluid from escaping inquantity from the injection module. Such vapor, depending upon thenature of the fluid, can be flammable and/or toxic. The waste system 36comprises a waste receiver 200 which communicates with a removable wastestorage tank 202 through a flexible conduit 204.

The waste receiver 200 is generally tubular member having an end opening206 which is covered by a septum 208. The waste receiver 200 isconnected to a movable support arm 210 which normally supports thereceiver 200 at a position where it is interposed between the needle 94and the analyzer inlet 12a. The needle 94 is advanced through the septum208 by movement of the carriage body after which purging of the syringebarrel is accomplished with the purging fluid being directed into thereceiver 200 to the tank 202 via the conduit 204.

The support arm is pivoted to a bracket 212 and is movable with respectto the bracket to pivot the receiver 200 from its normal waste receivingposition to a retracted position at which the receiver does notinterfere with the movement of the needle 94 into the analyzer inlet.The receiver 200 is pivoted to its retracted position by operation of asolenoid 214 which, when energized, moved the receiver to its retractedposition. When the solenoid 214 is deenergized a return spring, notillustrated, operates to return the receiver 200 to its waste receivingposition.

The support arm 210 carries a stop member 216 which projects from thesupport arm towards the end wall 44 of the frame 30 and towards thecarriage body 70. When the waste receiver 200 is positioned away fromits retracted position, i.e. when it is interposed between the needle 94and the analyzer inlet 12a, and the carriage 70 is advanced, the stop216 is engaged between the carriage 70 and the end wall 44 of the frame30 so that the actuator 34 cannot advance the needle 94 into the far endof the waste receiver 200. This prevents breakage of the syringe needlewhich would otherwise occur. When the waste receiver 200 is in itsretracted position the stop 216 is aligned with a slot 218 formed in thecarriage flange 78. Hence, when the needle 94 is advanced into theanalyzer inlet 12a the stop 216 passes through the slot 218 in thecarriage flange and does not impede movement of the carriage towards theanalyzer.

In the preferred embodiment of the invention the electrical conduits forthe various solenoids, the pressure conduits for the carriage body andplunger actuators and a sample fluid supply conduit to the syringe sidearm port 96 are all channeled into the injection module through one ofthe access openings 56 from the storage module. The storage module 16houses fluid control valves and associated parts for the variousconduits.

The storage Module The storage module 14 supports a plurality ofseparate containers 240 for fluid samples and purging solvents anddefines an extraction station 250 at which a fluid sample or purgingsolvent is extracted from a respective container and is directed to theinjection module 14. The individual containers 240 are supported by aplurality of the sample supporting tray members, or racks, indicated bythe reference characters 252-255 (see FIG. 6). The trays, or racks, areindividually removable from the storage module 16 with their associatedsample containers. An actuator assembly 258, forming a part of themodule 16, moves the container supporting trays in carrousel fashion sothat individual containers are successively moved to the extractionstation 250 from which the contents of the container at the extractionstation can be removed and directed to the injection module.

Referring now to FIG. 7, the storage module 16 comprises a support frame260 which is defined by a peripherally extending skirt 262 and acircular base plate 264 connected to the skirt. Side panels 266, 268extend perpendicularly with the respect to each other and generallytangentially with respect to the support base portion 264 and skirt 262to define a projecting corner of the storage module. The extractionstation 250 is located at the projecting corner of the module and thetrays 252-255 are circularly arranged over the support base 264.

The sample supporting tray members 252-255 are, in most respects thesame, and only the tray 253 is described in detail to the extent thatthe trays are identical. The tray 253 is shaped to approximate a frustumof a 90 circular segment having a circularly curved outer wall 270,radially extending side edges 272, 274 and a radially inner edge 276which extends between the side edges. A segmental radially inner traybody 280 extends between the edges 272, 274, 276 and terminates in acircular wall portion 282. The edges of the tray member are defined bylips which project from face to the body 280 and these lips, along withradially extending webs 284, rigidify the tray body portion 280. A pairof cylindrical bosses 285 extends from the body 280 beyond the webs 284.The bosses provide a detachable driving connection with the trayactuator assembly 258 as is described in greater detail presently.

A radially outer tray body portion 286 extends from the wall 282 and isrecessed from the body 280. The outer tray body portion 286 terminatesin the circumferential wall 270 and is rigidified by integral webs 292which extend radially outwardly from the wall 282 flush with the innertray body portion 280.

A circumferential series of sample container pockets 296 (preferably 15pockets for accommodating 15 separate containers) is disposedcircumferentially about the periphery of the outer tray body 186. Thepockets 286 are defined by semicircular recesses 298 formed in the traywall 270 and semicircular faces 300 formed on projecting lugs 302 at theradially outer ends of the webs 292. The recesses 298 and faces 300 arepositioned with respect to each other so that the container in eachindividual pocket is maintained accurately positioned in the pocket andconstrained against tipping, even if the tray shoulld be verticallyoriented.

The container support actuator 258 comprises a turntable assembly 310 towhich the individual trays 252-255 are detachably connected and aturntable drive mechanism 312 by which the assembly 310, and theattached trays, can be rotated with respect to the frame base 264. Theassembly 310 comprises a support shaft 314 which extends through theframe base 264 and is supported for rotation about an axis 315 by abearing unit 316 connected to the frame base. The projecting end of thesupport shaft 314 carries a circular tray support member 320 which isfixed to the shaft 314 for rotation about the axis 315 and which definesfour pairs of circumferentially spaced locating holes 321. A drum-likemember 322 is disposed between the tray support 320 and the frame base264 and is fixed to the shaft 314 for rotation with it.

A tray locking assembly 324 is disposed beyond the tray support 320 fromthe drum 322 and functions to permit the individual sample supportingtrays to be connected to and locked in place on the tray support member.

The locking assembly comprises a cylindrical body 330 which is fixed tothe end of the shaft 314 for rotation about the axis 315. Fourshouldered holes 332 are formed in the body 330 at locations spaced 90apart about the axis 315, with the holes extending generally parallel tothe axis. A circular retainer plate 334 is connected to the body 330 toclose the holes 332. Each of the holes 332 supports a shouldered detentpin 336 and a helical compression spring 338 which reacts between thedetent pin 36 and the retainer plate 334 so that the projecting end ofthe detent pin is urged from the body 330 towards the tray support 320.

Trays are inserted and locked in placed in the assembly 310 by cockingthe tray slightly with respect to the support member 320 and insertingthe inner edge 276 of the tray between the support member 320 and thebody 330 of the locking assembly. The end of the detent pin 336 isrounded so that the detent pin is forced into its shouldered hole 322against the force of the spring 338 as the tray is slid radiallyinwardly along the support member 320. When the locating bosses 285 arealigned with one pair of the locating holes 321 the tray is cockeddownwardly so that the bosses 285 extend through the associated locatingholes 321. At this juncture the webs 284 of the tray are engaged alongthe face of the support member 320 and the detent pin 336 is firmlyengaged with the tray body portion 280 to maintain the tray member incontact with the support member 320. The bosses 285 cooperate with theirrespective locating holes to enable the transmission of drive from therotatable support member 320 to the tray.

The drive mechanism 312 includes a reversible electric motor 340 havinga gear reduction (not shown) connected to its rotor shaft. An outputshaft of the gear reduction (not shown) extends through the frame base264 and an output pulley 344 is connected to the projecting end of thegear reduction output shaft. A drive belt 346 is reeved about the pulley344 and the drum 322 so that drive from the motor 340 is transmitted tothe turntable assembly 310 and thence to the individual trays supportedby the turntable assembly.

The containers 240 may be of any suitable construction but in theillustrated embodiment are glass vials which fit snuggly into thepockets 296. The containers 240 have a capacity of several millilitersof fluid and each container is closed by a septum 241 which is carriedby a removable cap 348.

The turntable assembly 310 moves the trays to position successivecontainer locations at the extraction station 250. Fluid in a containerat the extraction station is removed by a syringe-like dipper tubeassembly 352 and is directed to the injection module 14. The storagemodule 16 provides a container locating assembly which functions toprecisely align the containers at the extraction station with the dippertube assembly so that the dipper tube assembly is not damaged from beingadvanced into engagement with a misaligned container.

The storage module also houses a fluid container identifying systemwhich functions to identify the container at the extraction station bytray and pocket number as well as by whether the container is a samplecontainer or a solvent container. When a container has beenappropriately located at the extraction station and identified, thedipper tube assembly 352 is operated to enter the container, extractfluid from it, and direct the fluid to the injection module 14.

The container identification system comprises a container identifyingarrangement which ascertains the kind of fluid, i.e. sample fluid orsolvent, at the extraction station. When a sample fluid container islocated at the extraction station the system is enabled to perform acomplete purging and/or analysis cycle utilizing the sample fluid. Whena solvent container is located at the extraction station the system isautomatically conditioned to perform only a purge cycle to avoid theinjection of the solvent into the analyzer.

In the preferred embodiment of the invention, the

containers 240 each cooperate with SPDT micro switches 382, 384 when thecontainers are at the extraction station and the interaction between thecontainers and the switch depends on whether the containers are sampleor solvent containers. Three different containers 240a, 240b, and 2406are illustrated in FIG. 7. The containers 240a and 24011 arerepresentative of containers for solvent and sample fluid, respectively.The container 24% carries a removable ring 380a disposed about its cap348 and spaced from the projecting end of the cap. All of the fluidsample containers 24Gb are provided with a ring 380a of the characterdescribed, and in each case the ring is positioned remote from theprojecting end of the container cap 348. The container 240a carries aremovable ring 38% which is disposed about the cap 348 at its projectingend. All of the solvent containers 24% are provided with a similar ring38Gb disposed at the projecting end of the container cap 348.

As is best seen in FIGS. 7, the dipper tube assembly 352 comprises anextraction syringe needle assembly 430, an associated pneumatic fluidpurging system 432 (see FIG. 9) and an extraction syringe actuatorassembly 434. The actuator assembly 434 comprises a syringe needlesupport plate 436 which is connected to a single acting pneumatic ramincluding a cylinder 440 connected to the frame by a supporting bracket442 and a piston rod 444 extending between the cylinder 440 and thesupport plate 436. A radially inwardly projecting plate and 446 carriesthe needle assembly 430 for reciprocating motion towards and away from acontainer 240 at the extraction station. The plate 436 is connected toguide rods 450, 452 which extend through bores in the bracket 442 toguide the motion of the plate and the needle assembly as the plate isreciprocated by the ram 438. The guide rod 450 is surrounded by ahelical compression spring 454 reacts against the syringe support plate436 to urge the piston rod 44 towards its fully extended position. Whenthe piston rod retracted the plate and needle assembly 430 move towardsthe container and the needle assembly is thrust into the containerthrough its system.

FIG. 8 illustrates the needle assembly construction and the relationshipbetween the needle assembly and the container when the needle assemblyhas been forced into the container. The needle assembly 430 comprises acentral tubular needle 460 having a bulletnosed tip 462 for piercing theseptum and a central flow passageway 464. The central passagewaycommunicates with a sample fluid conduit 466 which extends from theneedle 460 to the side arm port of the injection syringe in theinjection module. The passageway 464 opens into the container adjacentthe tip 462 via ports 468 defined by a cross bore extending transverselythrough the needle. The ports are spaced from the tip so that theycannot core the septum and become blocked. When the needle assembly 430is properly positioned in the container, the ports 468 are well belowthe level of the liquid in the contaner.

The needle 460 is surrounded by a second tubular needle 470 having atapered end portion 472 fixed and sealed to the needle 460 at a locationspaced from the tip 462. The needle 470 defines a passageway 474surrounding the needle 460 which communicates with the purging system432 via a manifold 4'76 and with the container via ports 478 formed bytransverse holes extending through the wall of the needle 470. Theneedle 470 penetrates the container septum sufficiently that the ports470 are located within the container. The ports 478 open transversely ofthe needle 470 to prevent coring of the septum.

The purging system functions to force fluid from the container and intothe injection module by exposing the container to a controlled volume ofgas at a predetermined pressure. The volume of gas at the predeterminedpressure can be considered to possess a predetermined amount of purgingenergy proportional to the product of the pressure and the volume The PVenergy of the purging gas thus accurately determines the quantity offluid which is directed to the injection module. The waste system 36 ismaintained at atmospheric pressure throughout each purge cycle. As fluidis forced from the container to the injection module. the pressure inthe container decays until the purging gas has expanded to a pressureabout equal to atmospheric pressure.

As shown schematically by FIG. 9 the purging system 432 compises apressure regulating valve 54M), a pressure accumulator 56b2, anaccumulator control valve 504 and a vent valve 506. The regulating valve500 is connected to a source of pressurized gas by a supply conduit 538and a pressure manifold Slltl disposed in the storage module 16. Thepressure source can be of any suitable or available construction andpreferably provides air at pressures around 60 psig to the manifold 510through the conduit 508 which extends into the module 16.

The regulating valve drops the supply pressure to a predetermined lesserpressure, e.g. 25 psig. The valve 500 can preferably be adjusted so thatthe controlled pressure can be varied as desired by the operator. Agauge M2 is associated with the valve Silt) so that the magnitude of thecontrolled pressure can be monitored.

The accumulator 502 is communicated with the regulating valve 504) viathe control valve 504 which is a three-way solenoid operated valvehaving a small internal volume. The solenoid operator 504a isillustrated schematically and is operated from the control module 22.The control valve 504 has a first operating position in which theaccumulator is communicated to the regulating valve Silt) for chargingthe accumulator. This valve position is the normal" valve position andthe accumulator is nearly continuously maintained in its charged state.

The accumulator SQZ may be of any suitable or conventional constructionand is not illustrated in detail. The accumulator preferably has avolume of about microliters and, when charged, the accumulated gas is at25 psig. Because of the small accumulator volume it can be rapidlycharged from the regulator valve 500 when the control valve 504 is inits normal position.

The control valve solenoid 504a is operated from the control module 22to a second valve position wherein communication between the accumulatorand the regulating valve 500 is cut off and the accumulator iscommunicated to the dipper tube needle 470 via a low internal volumeconduit 520. This enables the accumulator to discharge into a fluidcontainer via the needle 470 so that fluid can be forced from thecontainer through the needle 460 to the injection module. Theaccumulator discharge is relatively rapid and accordingly the controlvalve 504 is only operated to its second, or accumulator discharging,position for about 4 seconds after which it returns to its normalposition and the accumulator is recharged.

In the preferred and illustrated system, the injection syringe has aninternal volume of about microliters and the sample conduit 466 has aninternal volume of about 10 microliters. It has been found that purgingsuch a system with a flow of fluid equal to about 10 times the combinedsyringe and conduit volumes reduces the quantity of residual material inthe purged volume to consistently low levels, e.g. to less than 0.01% byvolume. Accordingly, in the preferred system, the 100 microliteraccumulator, charged to 25 psig, is effective to produce a purgingvolume of solvent and/or sample fluid of about 200 microliters.

Some sample fluids have high vapor pressures at room temperature and ifthe accumulator were discharged into a container of such a fluid, thepartial pressure of the vapor combined with the PV energyof the purginggas could cause an excessive quantity of the fluid to be forced from thecontainer. Accordingly, in the preferred embodiment of the invention,after the needle assembly has been inserted into a container, the ventvalve 506 is opened to communicate the container to atmospheric pressurevia the needle 470, the conduit 520 and the valve 506. The valve 506 isoperated by a solenoid 506a which is energized and deenergized from thecontrol module 22.

After the vent valve 506 is opened to vent the container, it is reclosedand the container volume is substantially at atmospheric pressure. Thecontrol valve 504 is then actuated to discharge the accumulator into thecontainer so that a predetermined controlled pressure differential isapplied across the sample fluid, the fluid conduit 466 and the injectionsyringe assembly 72. In the preferred embodiment of the invention thecontrol module functions to allot a one minute period during whichpurging is accomplished. Purging is normally completed within thealloted time.

Referring further to P16. 9 the injection and storage modules 14, 16 areshown schematically by broken lines along with the various elements ofthe pneumatic system for operating the actuators in the modules.

As illustrated by FIG. 9 the injection syringe carriage actuator 34 iscommunicated to a. solenoid control valve 530 in the storage module by aconduit 543. The control valve 530 is in turn connected to the pressuremanifold 510 by a conduit 534. The valve solenoid 530a is energized anddeenergized from the control module 22 to control operation of thevalve. When the actuator 34 is operated to advance the syringe carriagetowards the analyzer inlet 12a or the waste receptacle, the valve 530 isoperated to direct high pressure air to the actuator 34. The carriage isretracted by operating the valve 530 to vent the actuator 34 so that theactuator return spring retracts the carriage.

The double acting plunger actuator 132 is communicated to the manifold510 at one end via a conduit 540, a control valve 542 and a conduit 544.The opposite end of the actuator 132 is communicated to the manifold viaa conduit 546, a control valve 548 and a conduit 550. The valves 542 and548 each are operated by solenoids 542a, 548a which are wired to thecontrol module. The valves 542, 548 are constructed like the 5 valve 530to either supply high pressure air to their respective ends of theactuator 132 or to vent the actuator, depending on energization of thesolenoids. When both valves direct pressurized air to the actuator 132the plunger is positively positioned by the actuator, as notedpreviously. This operation of the valves only occurs when the cross bar140 engages one or the other of the dosage stops 134, 136, which areschematically illustrated in FIG. 16, to enable retraction of the dosagestop element.

The single acting dipper tube actuator 434 is communicable to themanifold 510 via a conduit 554, a control valve 556 and a conduit 558.The control valve 556 includes a solenoid 556a wired to the controlmodule 22. The valve 556 is constructed and functions the same as thevalve 530.

As is apparent from FIG. 9 the pressure conduits 532, 540 and 546, aswell as the sample fluid conduit 466 all extend between the storage andinjection modules. Additionally, as noted above, the electric conductorsfor the dosage stops 134, 136 and the waste system solenoid 214 alsoextend from the storage module to the injection module.

While a single embodiment of the present invention has been illustratedand described in considerable detail, the invention is not to beconsidered limited to the precise construction shown. Numerousadaptations, modifications and uses of the invention may occur to thoseskilled in the art to which the invention relates and it is theintention to cover all such adaptations, modifications and uses whichfall within the scope or spirit of the appended claims.

We claim:

1. A method of purging material from a syringe comprising:

a. providing a syringe comprising a tubular barrel defining an internalpassageway having an axial end opening and a side opening and a plungersupported in said passageway for axial movement relative to said barrel,the imaginary solid intersection of said internal passageway and anextension of the perimeter of said side opening defining a space withinsaid internal passageway;

b. positioning said plunger in said barrel with a projecting plunger endportion disposed at least adjacent said side opening such that saidplunger end portion intersects said space defined by said imaginarysolid intersection;

c. directing a purging liquid fluid into said passageway through one ofsaid openings and discharging said fluid from said passageway throughthe other of said openings to purge said passageway; and

d. impinging said fluid on said projecting plunger end portion prior todischarging the fluid from said pas- 60 sageway to scrub said materialfrom said plunger while purging said passageway.

2. The method claimed in claim 1 further comprising placing said purgingfluid in a container which is closed by a septum, providing a septumpiercing dipper tube element comprising a first passageway having atleast a first port for communicating purging fluid from said containerto said chamber, and a second passageway separate from said firstpassageway having a second port for communicating said gas into saidcontainer, the container and spaced from said first passageway andfurther comprising piercing said septum with said dipper tube element sothat said first port is disposed in said container within the volumeoccupied by said purging fluid and said second port is disposed withinport whereby the purging fluid is forced from said container throughsaid first passageway.

1. A method of purging material from a syringe comprising: a. providinga syringe comprising a tubular barrel defining an internal passagewayhaving an axial end opening and a side opening and a plunger supportedin said passageway for axial movement relative to said barrel, theimaginary solid intersection of said internal passageway and anextension of the perimeter of said side opening defining a space withinsaid internal passageway; b. positioning said plunger in said barrelwith a projecting plunger end portion disposed at least adjacent saidside opening such that said plunger end portion intersects said spacedefined by said imaginary solid intersection; c. directing a purgingliquid fluid into said passageway through one of said openings anddischarging said fluid from said passageway through the other of saidopenings to purge said passageway; and d. impinging said fluid on saidprojecting plunger end portion prior to discharging the fluid from saidpassageway to scrub said material from said plunger while purging saidpassageway.
 2. The method claimed in claim 1 further comprisiNg placingsaid purging fluid in a container which is closed by a septum, providinga septum piercing dipper tube element comprising a first passagewayhaving at least a first port for communicating purging fluid from saidcontainer to said chamber, and a second passageway separate from saidfirst passageway having a second port for communicating said gas intosaid container, and further comprising piercing said septum with saiddipper tube element so that said first port is disposed in saidcontainer within the volume occupied by said purging fluid and saidsecond port is disposed within the container and spaced from said firstpassageway port whereby the purging fluid is forced from said containerthrough said first passageway.